<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    let date=prompt("请输入一个星期数")
    if(date==='星期一'){
      document.write('monday')
    }  else if(date==='星期二'){
      document.write('tuesday')
    }  else if(date==='星期三'){
      document.write('thrsday')
    }
   
  </script>
</body>
</html>